RDMA/i40iw: fix a potential NULL pointer dereference

A NULL pointer can be returned by in_dev_get(). Thus add a corresponding
check so that a NULL pointer dereference will be avoided at this place.

Fixes: 8e06af7 ("i40iw: add main, hdr, status")
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Xiyu Yang <[email protected]>
Signed-off-by: Xin Tan <[email protected]>
Reviewed-by: Leon Romanovsky <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

Author: sherlly

drivers/infiniband/hw/i40iw/i40iw_main.c

@@ -1225,6 +1225,8 @@ static void i40iw_add_ipv4_addr(struct i40iw_device *iwdev)
 			const struct in_ifaddr *ifa;
 
 			idev = in_dev_get(dev);
+			if (!idev)
+				continue;
 			in_dev_for_each_ifa_rtnl(ifa, idev) {
 				i40iw_debug(&iwdev->sc_dev, I40IW_DEBUG_CM,
 					    "IP=%pI4, vlan_id=%d, MAC=%pM\n", &ifa->ifa_address,